Heat stress induced cytosine methylation in the coding region of Rubisco activase (Rca) reveals its genotype-specific expression in contrasting wheat genotypes

Rising environmental temperature has become a major concern in global wheat production since it has critical effects on plant growth, development and yield. Elevated temperatures have become. Further understanding of the processes behind the development of heat tolerance is necessary for significant agricultural crops. Cytosine methylation in DNA plays an essential function in epigenetic regulation of gene expression at various developmental stages and environmental stress in plants. In this study, we report the comparative analysis of cytosine methylation in the coding region of the Rubisco activase (Rca) gene in heat tolerant (RAJ3765) and heat susceptible (HUW510) genotypes of wheat in four growth stages under control and heat-stressed conditions in CG, CHG and CGG contexts. We found that the overall 5-mC increased due to heat stress in HUW510 during tillering (25%), boot stage (25%), heading (48%) and anthesis (50%) as compared to RAJ3765 during tillering (21%), boot stage (4%), heading (4%) and anthesis (11%). Additionally, gene expression profiling by using qPCR at the different plant growth stages also showed the decline in the gene expression in the leaf samples in both the genotypes due to heat stress, with a minimum in the susceptible genotype at the anthesis stage. The study will increase the knowledge on the molecular regulation of photosynthetic pathways by cytosine methylation which would assist in selection and manipulation of heat tolerance in wheat.